Research On Resource Search Mechanism In Peer-to-Peer System

The past several years witness the rapid development of P2P systems. Efficient resource search scheme becomes the key technology of P2P systems. The characteristics of dynamics and anonymity of P2P can't ensure that all the peers will provide honest services and reliable resources. At the same time, although structured P2P systems have good scalability, the main issue exists in them is that they are stricted to exact match and don't support content based query. All these problems prohibit the rapid development of P2P systems. How to reduce searching cost and decrease the latency of locating resources and how to construct a safe efficient P2P system that supports content based query becomes an important subject of the P2P system research field. To solve the above two problems, this thesis focuses on the following researches.Firstly, the features of P2P networks are introduced. There are two classes of P2P network: structured and unstructured. This thesis introduces the classical resource search mechanism of these two kinds of P2P. Compared with structure P2P network, the resource search mechanism in unstructured P2P network doesn't need to maintain the Distributed Hash Tables (DHT). Thus, the calculation load of the system is reduced and the system has good usability and scalability.To solve the problem of existing DHT-based file storage systems being restricted to exact match and lacking semantic-based query, a DHT-based file storage system named CTI-Chord is proposed in this thesis. Using efficiently positioning method, CTI-Chord employs the category tree, which is the kernel structure as well as the innovation of CTI-Chord, to solve the problem of the disorder information management in P2P network and forms a novel information network framework. The distribution, acquisition and update of information are not based on key but property, which can support fuzzy search.Finally, to the problem of hostile service brought by node anonymity in P2P system, this thesis proposes a reputation aware resource finding algorithm. This algorithm is based on routing indices (RIs) algorithm and adopts the conception of reputation to efficiently restrain the deceiving behavior of hostile nodes in P2P system and reduce the messages load in the system, which can ensure the reliability and safety of the services.Simulation results show that the resource search schemes presented in this thesis not only reduce the searching cost and decrease the latency to locate resources in P2P system effectively, but also provide content-based query and ensure the safety of the whole system.